Thank you for contacting us.
You could just download our latest version for RadControls for ASP.NET AJAX. Installing it you will get the .NET 3.5 assemblies as well, along with the .NET 4 assemblies.
The easiest way for you to download and install the product is using our new tool Control Panel. It could install and upgrade all your Telerik Developers Tools from a single application and could be found at the first page which is displayed right after logging in to your account.
Please do not hesitate to contact us if you experience any issues.
the Telerik team
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